The present invention is generally directed to a power system for providing power to a plurality of loads, such as, a computer system. The present invention is more particularly directed to such a power system which is capable of being sourced by redundant sources to provide flexibility and reliability.
There are many applications where a power system must provide reliable power to the system which it powers. A computer system is one example.
Previous computer systems were generally provided with their own AC input power supplies. These AC “front-end” supplies produced positive DC voltage outputs. From these positive DC voltage outputs, power subsystems produced mid- and low-rail voltages. When these computer systems needed to be adapted for use in the Telecom industry, power system redesign was required due to the −48 V DC voltages available to power the computer system. In the end, the computer system power supplies for the Telecom industry were difficult to design, required higher component density, were more expensive, and required long lead-times. To provide power supply redundancy for reliability, two similar supplies were generally employed.
It is generally desirable for computer systems in general, and those used in the Telecom industry specifically, to be continuously powered. Telecom systems utilized in the Telecom industry are generally rack mounted as is the telephone equipment. The racks are generally standardized to accept computer equipment, such as computer servers, hereinafter referred to as a load, of a preset width of, for example, 19 inches, and a whole number of height units referred to as “U's”.
Once a rack is configured with its loads, it is then necessary to match it with a rack of power sources. It would be desirable to be able to configure the power distribution system so that all of the loads would remain fully powered at all times. This would require redundancy in power sources. Unfortunately, redundancy of this kind has been difficult to obtain in the past. This is due to the fact that loads could not use the −48 V DC commonly directly available in the Telecom industry, but instead, each had its own power supply to provide required DC voltages from AC inputs. As a result, power distribution systems incorporating loads, such as computer equipment, for use in the Telecom industry, required power input redesign to enable the equipment to be powered directly from the standard DC voltage available in the Telecom industry environment. One such power distribution system directed to this end which provides full power source redundancy is disclosed, for example, in copending U.S. patent application Ser. No. 10/773,008, filed Feb. 6, 2004, and titled REDUNDANT INPUT POWER SYSTEM, which application is incorporated herein by reference. The system disclosed in this application permits loads, such as computer equipment, to be standardized for receipt within a rack of preset width and having a height equal to a whole number of height units. This also permits standardization of power sources. For example, six AC power supply providing 1,000 watts each of DC power at −48 V DC may have a rack height of 3 U. Similarly, multiple standard 2,000 watt, −48 V DC battery supply feeds from the telecom industry's bus bar infrastructure are normally available above the racks. Both the AC sources and DC sources may provide the same DC output voltage of, for example, −48 V DC.
When configuring a power distribution system, once a rack of loads is configured, it is then necessary to configure the power sources for those loads. As previously mentioned, it is desirable to so configure the power sources such that the sources are interconnected with the loads in a manner which provides complete and continuous power to each of the loads notwithstanding failure of one of the power sources. This provides the desired redundancy. Further, it would be most desirable to so configure the power distribution system such that the number of power sources is reduced to a minimum while providing the desired redundancy. The present invention addresses these issues and requirements.